In 2003, Salvador Mu oz Vi as published Teor a contempor nea de la Restauraci n. Two years later, he wrote Contemporary Theory of Conservation, a different, revised version of the first work. In these books, the philosophy of conservation was analyzed, and, building from different authors and sources, an alternative approach was outlined. Since 2005, the author has continued working on this topic, revising the ideas presented in these books, and developing new ones. Many of these ideas were presented in papers or in lectures. On Theoretical and Ethical Principles of Conservation gathers together fifteen of these contributions. While the papers and lectures included in this volume were not conceived as part of a whole, a coherent line of thinking can be easily detected: in all of them, the core notions of conservation ethics are discussed and analyzed. In different ways, they all aim at showing that, simply put, the so-called 'principles of conservation' are not what they may seem at first sight. Heritage conservation is a well-established activity in many societies - an activity that does work, and that serves its purposes in an overly successful way; however, the reflections presented in this volume suggest that conservation might benefit from a different, less traditional interpretation of some of its ethical and theoretical tenets.